Adult-type rhabdomyosarcoma

Rhabdomyosarcomas more commonly afflict children and adolescents.  It is rare in adults, accounting for 1% of all soft tissue sarcomas.  In adults, rhabdomyosarcomas are embryonal (34%), alveolar (23%) or pleomorphic (43%), rarely spindle cell or sclerosing.  Adult-type excludes embryonal and alveolar types. Most so-called rhabdomyosarcomas in adults within the internal trunk are in fact dedifferentiated liposarcomas with heterologous rhabdomyoblastic differentiation, as evidenced by MDM2 and CDK4 amplification.  


Clinical features

True adult rhabdomyosarcomas occur predominantly in the lower limb, trunk wall or upper limb.


Macroscopic appearances

Tumours most often arise in deep soft tissues, often striated muscle.  They are typically circumscribed and lobulated.


Three morphological types have been described, based on the predominant cellular pattern:

The mitotic rates are very variable, as is the extent of necrosis. Cross striations are not seen.


Positivity for desmin and myogenin is a sine qua non.  

    spindle cell pleomorphic mixed total  
Desmin 25/251 16/161, 10/113   16/161 57/571
Myogenin 25/251 16/161 16/161 57/571
Myoglobin   10/113    
SMA 7/251 0/161, 25/352, 6/83   5/161 12/561
HHF35   11/113    
Sarcomeric actin   6/93    
Fast myosin   5/53    
Caldesmon 1/251 0/161 1/161 2/471
CD34 4/251 1/161 2/161 7/531
AE1/AE3 2/251 3/161 6/161 11/551
EMA 4/251 3/161 5/161 12/281
S-100 0/251 1/161, 0/113 0/161 1/561
MDM2 1/251 1/161 0/161 2/551
CDK4 0/251 2/161 0/161 2/551



Differential diagnosis


Surgery when possible, with adjuvant radiotherapy or chemotherapy.


The five year survival is approximately 50%.  Spindle cell rhabdomyosarcoma is aggressive compared with the childhood counterpart.  Sclerosing rhabdomyosarcoma also has a poor prognosis.


1 Stock N, Chibon F, Binh MB, Terrier P, Michels JJ, Valo I, et al. Adult-type rhabdomyosarcoma: analysis of 57 cases with clinicopathologic description, identification of 3 morphologic patterns and prognosis. Am J Surg Pathol. 2009 Dec;33(12):1850-9.

2 Furlong MA, Mentzel T, Fanburg-Smith JC. Pleomorphic rhabdomyosarcoma in adults: a clinicopathologic study of 38 cases with emphasis on morphologic variants and recent skeletal muscle-specific markers. Mod Pathol. 2001 Jun;14(6):595-603.

3 Gaffney EF, Dervan PA, Fletcher CD. Pleomorphic rhabdomyosarcoma in adulthood. Analysis of 11 cases with definition of diagnostic criteria. Am J Surg Pathol. 1993 Jun;17(6):601-9.

This page last revised 29.3.2010

©SMUHT/PW Bishop